GB677707A - Improvements in or relating to commutators - Google Patents

Abstract

677,707. Making commutators. WESTING- HOUSE ELECTRIC INTERNATIONAL CO. Feb. 7, 1951 [March 17, 1950], No. 2983/51. Classes 83 (ii) and 83 (iv). A process of making a commutator and securing it to the armature coil-ends of a dynamo-electric machine comprises clamping together an assembly of copper and unhardened mica segments, heating said assembly, mainly from the inside, to a commutator-seasoning temperature, cooling and assembling the seasoned commutator on the armature and soldering the ends of the armature coils to the copper segments, the seasoning temperature being at least as high as the soldering temperature. A dynamo-electric machine comprises a stator 1, a rotor 2 on a shaft 3, an armature core 4, armature windings 5 and a commutator 6. The commutator comprises copper segments 10 separated by mica segments 11 and having necks 12 to which are soldered the coil-ends 13. The two ends of the commutator assembly have V-grooves 14 for receiving clamps 15 and 16 drawn together by bolts 17. Insulating V-ring members 18 are disposed between the segments and the clamps. For seasoning, the assembled commutator segments are squeezed together by an inner split clamp 22 and an outer solid clamp 23. A heatinsulating layer 24 is interposed between the clamp 22 and the segments. The clamped commutator is placed in a pan 28 supported in a solder pot 26 containing molten solder 27, the level of which can be raised or lowered. The bottom of the pan has an opening 30, and a yieldable heat-resistant gas jet 31 surrounding the opening provides a fluid-tight joint between the commutator and the pan. The solder level, which is initially below the bottom of the pan, is raised to immerse the interior of the commutator assembly to effect the seasoning, after which the clamping rings 21 are retightened and the assembly allowed to cool. The V-grooves 14 and the current-collecting surface 7 are then machined to final dimensions. If the bore had been machined prior to seasoning it is painted with a mixture of clay and water to prevent adhesion of solder to the bore. The seasoned assembly is mounted on the clamping V-rings 15 and 16 which are carried by a sleeve 33 which supports the armature-core 4. The coil ends 13 are then connected to the necks 12 of the respective copper segments 10 by placing the commutator end of the machine in a solder pot 36, Fig. 3. This pot has a cup 37 which surrounds the commutator but leaves the necks 12 exposed. An asbestos sealing ring 38 ensures a fluid-tight joint between the necks 12 and the cup 37. The solder level is raised in the pot 36 until the necks 12 are immersed to effect the soldering together of the necks and the coil ends. High temperature solder is used for both seasoning and soldering, the solder pot temperature being approximately 476‹ C. and the commutator segments reach a temperature of from 300‹ to 350‹ C. Liquids, other than solder, may be used in the seasoning operation.